1. Center for Polymer Studies and Departments of Physics, Chemistry, Biomedical Engineering, and Physiology, Boston University, Boston, MA 02215, USA
2. Department of Physics, Yeshiva University, 500 West 185th Street, New York, NY 10033, USA
3. Departament de Física Fondamental, Universidad de Barcelona, Diagonal 647, 08028 Barcelona, Spain
4. Minerva Center and Department of Physics, Bar-Ilan University, 52900 Ramat-Gan, Israel
5. Dipartimento di Fisica, Univ. Messina, Vill. S. Agata, C.P. 55, I-98166 Messina, Italy
6. Center for Studies in Physics and Biology, Rockefeller University, New York, NY 10021, USA
7. Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, D-55128 Mainz, Germany